Not much is happening at the Large hadron Collider, as it’s being rebuilt, but it is celebrating its 10th anniversay of reaching maximum 3.5 TV energy, and there’s a new record magnetic field strength.
On 25 March, a niobium-tin superconducting magnet achieved a peak magnetic field of 16.5 tesla.
By way of comparison, the niobium-titanium superconductor currently used for the magnets of the LHC operate at a nominal field of 8.3 tesla.
Niobium-tin is the material being used for some of the new magnets in the High-Luminosity LHC, the successor to the LHC, which will operate at a nominal 12 tesla. Now researchers have coaxed an even stronger field out of niobium-tin.
The magnet consists of two superimposed flat coils in the shape of a racetrack. It will now be dismantled and rebuilt with three superimposed flat coils.
On 30 March 2010, exactly ten years ago, a Tuesday, a metaphorical champagne bottle was smashed across the bow of the Large Hadron Collider (and several non-metaphorical ones were popped) as CERN’s flagship accelerator embarked upon its record-breaking journey to explore strange new worlds at the high-energy frontier: it collided protons at an energy of 3.5 teraelectronvolts (TeV) per beam for the first time. All four of the LHC’s big detectors – ALICE, ATLAS, CMS and LHCb – saw high-energy collision debris for the first time
Since then, the largest scientific instrument ever built has enabled scientists to study a variety of physics phenomena, with its crowning achievement being the discovery of the Higgs boson in 2012.
The LHC wasn’t built just to find the Higgs boson – or prove that it didn’t exist! Over the last ten years, it has allowed scientists to test the Standard Model of particle physics with higher precision than ever before, demonstrating the theory’s robustness. In addition to the proton–proton collisions that are the LHC’s staple, scientists have used collisions of lead nuclei to recreate and examine the conditions that prevailed in the very early universe, when quarks and gluons existed freely. And the Higgs boson itself has brought entirely new perspectives to physics – an elementary particle with no intrinsic angular momentum, the first of its kind.
1977 – the LHC was first conceived.
2008 – Proton beams flew through the machine for the first time.
2009 – From the first low energy collisions up to 1.1 TeV, exceeding Fermilab’s Tevatron.
The LHC’s saga has just begun. The machine is expected to operate until the end of the ’30s and nearly 95% of the LHC’s promised data volume is still to come.
In the coming weeks, to mark the first ten years of one of humanity’s greatest scientific endeavours, we will publish a series of features on home.cern covering the physics results that have shaped our understanding of the universe – from probing the Standard Model and the early universe, to the new vistas that the Higgs boson has opened up, to the mysteries of dark matter and more. Celebrate ten years of LHC physics with us.
From 10 Mar 2020. Analysis of LHCb results yield surprises
The decay in question is the decay of a B0 meson, which is made up of a bottom quark and a down quark, into a K* meson (containing a strange quark and down quark) and a pair of muons. It is a rare process: The Standard Model predicts only one such decay for every million B0 decays. In many theories that extend the Standard Model, new unknown particles can also contribute to the decay, resulting in a change of the rate at which the decay should occur.
There’s a deviation from Standard Model of 3 sigma. The gold standard is 5 sigma.
Note from mollwollfumble, actually 3 sigma isn’t bad, I start believing things at 3 sigma. That’s a P value of 0.00135 << 0.05.
19 Feb 2020 Antihydrogen news
New measurements of quantum effects in antihydrogen match those predicted for normal hydrogen. Among other things, they’ve measured the lamb shift for antihydrogen (a bit of history, predicting the Lamb shift defeated more than one top physicist some seventy years ago).
The ALPHA team creates antihydrogen atoms by binding antiprotons delivered by CERN’s Antiproton Decelerator with positrons. It then confines them in a magnetic trap in an ultra-high vacuum, which prevents them from coming into contact with matter and annihilating. Laser light is then shone onto the trapped atoms to measure their spectral response.
The team previously used this approach to measure other quantum effects in antihydrogen, the latest being a measurement of the Lyman-alpha transition (a much easier thing to measure).
Both the fine structure and the Lamb shift are small splittings in certain energy levels (or spectral lines) of an atom, which can be studied with spectroscopy. The fine-structure splitting of the second energy level of hydrogen is a separation between the so-called 2P3/2 and 2P1/2 levels in the absence of a magnetic field. The splitting is caused by the interaction between the velocity of the atom’s electron and its intrinsic (quantum) rotation. The classic Lamb shift is the splitting between the 2S1/2 and 2P1/2 levels, also in the absence of a magnetic field.
It is the result of the effect on the electron (or positron) of quantum fluctuations associated with virtual photons popping in and out of existence in a vacuum.
From 13 Feb 2020, ATLAS releases 13-TeV open data for science education. The collaboration has made public the data of 1 quadrillion proton-proton collisions from the LHC’s last run.
Here’s your chance to do some citizen science.